97. The interrogative pronouns now in use are _who_ (with the forms _whose_ and _whom_), _which_, and _what_.
There is an old word, _whether_, used formerly to mean which of two, but now obsolete. Examples from the Bible:--
_Whether_ of them twain did the will of his father?
_Whether_ is greater, the gold, or the temple?
It may be a question _whether_ of these unfortunate persons had the greater soul.
[Sidenote: _Use of_ who _and its forms._]
98. The use of _who_, with its possessive and objective, is seen in these sentences:--
_Who_ is she in bloody coronation robes from Rheims?--DE QUINCEY.
_Whose_ was that gentle voice, that, whispering sweet, Promised, methought, long days of bliss sincere?--BOWLES.
What doth she look on? _Whom_ doth she behold?--WORDSWORTH.
From these sentences it will be seen that interrogative _who_ refers to _persons only_; that it is not inflected for gender or number, but for case alone, having three forms; it is always third person, as it always asks _about_ somebody.
99. Examples of the use of interrogative _which_:--
_Which_ of these had speed enough to sweep between the question and the answer, and divide the one from the other?--DE QUINCEY.
_Which_ of you, shall we say, doth love us most?--SHAKESPEARE.
_Which_ of them [the sisters] shall I take?--_Id._
As shown here, _which_ is not inflected for gender, number, or case; it refers to either persons or things; it is selective, that is, picks out one or more from a number of known persons or objects.
100. Sentences showing the use of interrogative _what_:--
Since I from Smaylho'me tower have been, _What_ did thy lady do?--SCOTT.
_What_ is so rare as a day in June?--LOWELL.
_What_ wouldst thou do, old man?--SHAKESPEARE.
These show that _what_ is not inflected for case; that it is always singular and neuter, referring to things, ideas, actions, etc., not to persons.
101. The following are all the interrogative forms:--
_Nom._ who? which? what? _Poss._ whose? -- -- _Obj._ whom? which? what?
In spoken English, _who_ is used as objective instead of _whom_; as, "_Who_ did you see?" "_Who_ did he speak to?"
[Sidenote: _To tell the case of interrogatives._]
102. The interrogative _who_ has a separate form for each case, consequently the case can be told by the form of the word; but the case of _which_ and _what_ must be determined exactly as in nouns,--by the _use_ of the words.